Transformer fold-out winding tap which is integral with transformer winding

ABSTRACT

A winding tap for a transformer coil consists of an integral portion of the winding at the outer surface of the full coil which is bent or folded outwardly. The outwardly bent portion receives a compression lug to serve as a tap for making connection to an intermediate portion of the winding.

o m, v I i Sines iei 1 1 1 1 fi m Ruckel et al. 1 Apr. 1%, 1973 [5 TRANSFQRMER FOLD-OUT WENDHJG References Cited 53 WHTH UNITED STATES PATENTS 721,289 2/1903 Depp ..336/l92 X [75] Inventors: James R. Ruckel, King of Prussia, 1836948 12/1931 Andfrsonm ""336/2O9X 7 Pa: Charles P- Rizm Clementon 2,958,059 10/1960 Jarvre "336/192 N Silvio A M aJr Philadel: 3,271,717 9/1966 Gilbert ....336/209 pm; Pa 3,287,681 11/1966 Caldwell ..336/209 Primary Examiner-E. A. Goldberg [731 Asslgnee' 'f g Corporahnn Attorney-Samuel Ostrolenk et a1.

[22] Filed: July 29, 1971 [.57] ABSTRACT PP 167,174 winding tap for a transformer coil consists of an inv tegral portion of the winding at the outer surface of 52 us. (:1. ..336/107, 336/192, 336/209 the full Coil which is bent or folded outwardly- The [51] Im. Cl .L ..H0lf 15/10 outwardly bent portion receives a compression g to [58] Field of Search ..336/ 192, 209, 60, serve as a tap for making connection to an intermediate portion of the winding.

7 Claims, 6 Drawing Figures TRANSFORMER FOLD-OUT WINDING TAF WIIICII IS INTEGRAL WITII TRANSFORMER WINDING BRIEF SUMMARY OF THE INVENTION This invention relates to transformer windings, and more particularly relates to a tap arrangement for transformer windings in which the tap is made of an integral portion of the winding itself by looping out a portion of the transformer windings at the outer surface of the coil. I I

The provision of taps for electrical windings is well known. Such taps are frequently made by welding a conductive member to a portion of the winding where the tap is to be made. A plurality of such welded taps may be used. The use of welded taps requires the provision of special welding equipment which is set up for each individual tap as it is to be welded in place as the winding operation progresses. Thus, the use of welded taps increases manufacturing time and cost and requires the attention of skilled operators.

In accordance with the present invention, one or more taps can be made in the outer surface of a transformer winding without the need for special tools or special skills on the part of the personnel used to assemble the coil. Thus, the winding operation proceeds in the normal manner until the point is reached on the wire where a tap is desired. At this point, the conductor, which may be conventional magnet wire, is simply bent outwardly and then inwardly and then the winding is continued, leaving an outwardly folded loop in the winding which is a continuous and integral portion of the winding. All insulation on the wire may be removed on the outer and inner surfaces of the loop. This loop may later be used to receive a conventional screw-type compression lug to which connection may be made. Connection to the taps may then be changed manually or by conventional tap changing equipment, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top view of a conventional type of a transformer winding which may be used for one phase of a high-power air cooled transformer.

FIG. 2 is a cross-sectional view of the coil of FIG. I when taken across the section line 2 2 in FIG. ll.

FIG. 3 is a schematic diagram of the winding configuration of the transformer winding shown in FIGS. I and 2.

FIG. 4 is an elevational view of the winding of FIGS. 1, 2 and 3 when adapted with tap loops in accordance with the present invention.

FIG. 5 is a top view of a portion of one of the tap loops of the present invention, with the insulation-tape covering for the winding having been removed for clarity.

FIG. 6 is a cross-sectional view of FIG. 5 taken across the section line 6 6 in FIG. 5.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIGS. I, 2 and 3, there is shown a conventional transformer coil assembly which could be used, for example, in a Class H dry-type transformer wherein the transformer primary voltage is 4,160 volts, while the secondary voltage for. a three-phase transformer is either 480 volts or 277 volts with the KV A rating of the transformer being 1,000. The transformer may then be provided with suitable taps which could provide 2% percent changes in output voltage.

The figures show a coil assembly for only a single phase of such a transformer, where the coil assembly contains an interior insulation support tube 20 which is adapted to be mounted on a suitable transformer core (not shown). Tube 20 will carry both the primary and secondary windings of the transformers as schematically illustrated in FIG. 3.

Thus, in FIG. 3, the winding is shown as deposited on the coil 20 in six layers. The first two layers form the secondary or low-voltage windings and include layers 21 and 22, which are wound concentrically with respect to one another. It will be noted that layer 21 starts at the terminal 23, while layer 22 ends at the lowvoltage winding terminal 24. The high-voltage winding or primary winding is then wound over the exterior of the low-voltage winding layers 21 and 22 and is wound in layers shown in FIG. 3 as concentric layers 25 through 28. It will be noted that layer 28 is the outermost layer of the coil assembly and it is the layer 28 which will contain the various taps shown in FIG. 3 as taps 29 through 34. The high-voltage winding is then I provided with two main terminals, shown in FIG. 3 as consisting the start of the winding at terminal 35 and the finish of the winding shown as terminal 36.

In one specific embodiment of the invention, layers 21 and 22, which form the low-voltage winding, may be formed of twelve strands of aluminum wire connected in parallel, where each strand may have a rectangular cross-section of 0.150 inches by 0.500 inches. Each of the layers 21 and 22 contain seven turns of this 12- strand conductor. Note that each of the strands may be suitably coated with an insulation covering of conventional type.

The high-voltage winding layers 25, 26 and 27 each consist of 53 turns of rectangular aluminum wire having the dimensions of about 0.115 inches by-0.4l5 inches. The outermost layer 28 may then consist of a winding containing sixteen turns to tap 33, five turns between taps 31 and 33, five turns between taps 29 and 31, five turns between taps 30 and 32, five turns between taps 32 and 34, and 15 turns between tap 34 and terminal 36. Thus, the outermost layer 28 will contain 51 turns. Note that the taps 29 to 341 will be interconnected in various appropriate and well-known combinations in order to give 4i 2% percent taps for adjustment of the output voltage of the coil assembly.

In FIGS. I and 2 it will be seen that a plurality of spacer sticks are conventionally used to separate the various layers so that air can move along the axis of the coil assembly to cool the surfaces of the windings. Thus, a first plurality of spacer sticks, typically the spacer stick 40 along with eleven other sticks on the same radius as stick 40, are disposed between insulation tube 20 and the first layer 21 of the low-voltage winding. The low-voltage winding 21, which is insulated in the usual manner, then has a plurality of spacer sticks, such as sticks 41, disposed on its outer surface and oriented parallel to the axis of layer 21 and the second low-voltage winding layer 22 is wound over the spacer sticks i1. Note that the secondary winding terminals 23 and 2textend beyond the axial end of the coil assembly, as shown in FIG. 2.

Thereafter, a further set of spacer sticks 43 is placed on the outer surface of low-voltage winding 22 and a high-voltage barrier tube 44, which may be of any desired insulation material, is placed over spacer sticks 43. A further set of spacer sticks 45 is applied over the outer surface of insulation barrier 44 and the first layer 25 of the high-voltage winding is wound on the spacer sticks 45. A further cylindrical group of spacer sticks 46 is then placed on the outer surface of layer 25 and the next high-voltage layer 26 is wound atop the spacer sticks 46.

Thereafter, an insulation layer, of any desired type (shown as insulation tube 47 in FIG. 2), is wound on the outer surface of high'voltage layer 26 and the third high-voltage layer 27 is wound on top of the insulation layer 47. Thereafter, a plurality of insulation sticks 48' are placed on the outer surface of layer 27 and the last high-voltage layer 28 is wound on top of sticks 48.

FIG. 2 shows the staggered appearanceof taps 29 to 34 which come off the high-voltage layer 28 in the manner schematically illustrated in FIG. 3. It is to be noted that the arrangement described heretofore in connection with FIGS. 1, 2 and 3 is of the type well i known to the art, where the taps 29 to 34 conventionally are made by welding to the winding layer 28 during the winding operation and when the tap position is reached on the coil..As pointed out previously, this requires moving welding apparatus into position with respect to the coil winding assembly when the weld is to be made and, after the weld is made, removing the welding assembly to permit the winding to continue until the next tap position is reached.

In accordance with the present invention, and as shown in FIGS/i to 6, a novel tap configuration is used which eliminates the need for welding the taps. Referring now to FIGS. 4, and 6, and particularly to FIGS. 5 and 6, there is illustrated the construction used for making the tap 29 of FIGS. 1, 2 and 3, which will be identical to the construction used for all of the other taps to be made.

Referring first to FIG. 5, there is shown three of the convolutions or turns of the five-turn section of the winding located between taps 29 and 31 in FIG. 3. These turns are designated as turns 50, 51 and'SZ in FIG. 5, where the right-hand end turn or convolution 52 extends sufficiently far to overlie the spacer sticks 48 sothat the free end of turn 52 is appropriately supported as shown in FIG. 6.

In order to form the tap 29, a portion of the turn or convolution 52 is bent to the U-shaped bend 53 during the winding process and before the wire is cut at the right-hand end of the convolution 52. The U-shaped folded or bent portion 53 may then receive a conventional screw-type compressional lug 54, as shown in 'FIGS. 5 and 6. Note that all insulation will be removed from the outer surfaces of U-shaped portion 53 before it is inserted into the opening 55 of the lug 54. The screw 56 is then tightened to press the U-shaped portion 53 againsta conductive insert 57, thereby to make a firm electrical connection between the lug 54 and the U-shaped bent portion 53, thereby to define the tap 29.

' In order securely to hold the tap 20 in position, an insulation sheet 60 (FIGS. 4 and 6) may be placed over the outer surface of the coil assembly, where the sheet 60 may have a thickness of 0.030 inches and may contain openings which were pre-formed in the sheet to have been laid in place,'the outer surface of the coil may be wound with a suitable glass tape. layer which securely holds in position the individual insulation sheets 61 to 66 and forms the outer insulation coating for the main coil assembly.

It is to be noted that the wire used in forming the coil may be a wire which has a varnish insulation, a wrapped insulation, or the like. Note that such insulation may be appropriately stripped from the tap loops, such as loop 53 in FIGS. 5 and 6, before the winding is bent to its looped shape.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now. be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be A limited, not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A winding tap for a winding of conductive wire; said winding of conductive wire comprising a plurality of coaxial convolutions of a continuous wire extending between first and second ends; said winding tap being defined by an integral outwardly looped portion of said wire in an outermost convolution of said plurality of coaxial convolutions; said outwardly looped portion being an integral part of said continuous wire and being continuous therewith and having a generally flattened U shape in cross-section; said outwardly looped portion of said wire being spaced from said first and second ends of said wire whereby said conductive wire extends from the ends of said U-shaped portion of said wire; said conductive wire being generally rectangular in cross section and having a width in the axial direction of said winding which is greater than its height.

2. The winding tap of claim 1 which further includes a connection lug means connected to said outwardly looped portion of said wire; said connection lug means defining a connection region for making connection to said winding tap.

3. The winding tap of claim 1 which further includes terminal means connected to said first and second ends of said continuous wire.

4. The winding tap apparatus of claim 3 which further includes a plurality of further winding taps laterally displaced from one another along the axis of said winding, each identical in construction to said winding tap, and each being spaced from one another along the length of said continuous wire.

5. The winding tap apparatus of claim 4 which further includes a further connection lug means connected to each of the said plurality of further winding taps of said continuous wire.

6. The winding tap of claim 1 wherein said conductive wire has a width-to-height ratio of about 5 to 1.5.

7, The winding tap of claim 1 which further includes an insulation covering extending around the full outer surface of said winding; said winding tap extending through said insulation covering. 

1. A winding tap for a winding of conductive wire; said winding of conductive wire comprising a plurality of coaxial convolutions of a continuous wire extending between first and second ends; said winding tap being defined by an integral outwardly looped portion of said wire in an outermost convolution of said plurality of coaxial convolutions; said outwardly looped portion being an integral part of said continuous wire and being continuous therewith and having a generally flattened U shape in cross-section; said outwardly looped portion of said wire being spaced from said first and second ends of said wire whereby said conductive wire extends from the ends of said U-shaped portion of said wire; said conductive wire being generally rectangular in cross-section and having a width in the axial direction of said winding which is greater than its height.
 2. The winding tap of claim 1 which further includes a connection lug means connected to said outwardly looped portion of said wire; said connection lug means defining a connection region for making connection to said winding tap.
 3. The winding tap of claim 1 which further includes terminal means connected to said first and second ends of said continuous wire.
 4. The winding tap apparatus of claim 3 which further includes a plurality of further winding taps laterally displaced from one another along the axis of said winding, each identical in construction to said winding tap, and each being spaced from one another along the length of said continuous wire.
 5. The winding tap apparatus of claim 4 which further includes a further connection lug means connected to each of the said plurality of further winding taps of said continuous wire.
 6. The winding tap of claim 1 wherein said conductive wire has a width-to-height ratio of about 5 to 1.5.
 7. The winding tap of claim 1 which further includes an insulation covering extending around the full outer surface of said winding; said winding tap extending through said insulation covering. 